Relationships among developmental stage, metamorphic, timing, and concentrations of elements in bullfrogs (Rana catesbeiana)
Joel W. Snodgrass,1,2 William A. Hopkins,3 and John H. Roe3,4
of Biological Sciences, Towson University, 8000 York Road, Towson, Maryland
21252, USA 2Environmental and Occupational Health Sciences
Institute, and Consortium for Risk Evaluation with Stakeholder Participation
(CRESP), Rutgers University, Piscataway, New Jersey 08854, USA
Abstract: We collected bullfrog (Rana catesbeiana) larvae from a coal combustion waste settling basin to investigate the effects of developmental stage and timing of metamorphosis on concentrations of a series of trace elements in bullfrog tissues. Bullfrogs at four stages of development (from no hind limbs to recently metamorphosed juveniles) and bullfrogs that metamorphosed in the fall or overwintered in the contaminated basin and metamorphosed in the spring were analyzed for whole-body concentrations of AI, V, Cr, Ni, Cu, As, Pb, Cd, Zn, Ag, Sr, and Se. After the effects of dry mass were removed, tissue concentrations of six elements (AI, V, Cr, Ni, Cu, As, and Pb) decreased from the late larval stage through metamorphosis. Decreases in concentrations through metamorphosis ranged from 40% for Cu to 97% for AI. Tissue concentrations of these elements were also similar or higher in spring; Al and Cr concentrations were 34 and 90% higher in the spring, respectively, whereas As, Ni, Cu, and Pb concentrations were <10% higher. Concentrations of Cd, Se, and Ag varied among seasons but not among stages; Cd and Ag concentrations were 40 and 62% lower, respectively, and Se concentrations were 21 % higher in spring. Concentrations of Zn varied only among stages; concentrations decreased gradually through late larval stage and then increased through metamorphosis. Concentrations of Sr varied among stages, but this variation was dependent on the season. Concentrations of Sr were higher in larval stages during the spring, but because concentrations of Sr increased 122% through metamorphosis in the fall and only 22% in the spring, concentrations were higher in fall metamorphs when compared with spring metamorphs. Our results indicate that metamorphosis and season of metamorphosis affects trace element concentrations in bullfrogs and may have important implications for the health of juveniles and the transfer of pollutants from the aquatic to the terrestrial environment.
Keywords: Coal combustion waste, Amphibians, Trace elements, Metamorphosis, Larval period
SREL Reprint #2684
Snodgrass, J. W., W. A. Hopkins, and J. H. Roe. 2003. Relationships among developmental stage, metamorphic, timing, and concentrations of elements in bullfrogs (Rana catesbeiana). Environmental Toxicology and Chemistry 22:1597-1604.